a) Field of the Invention
This invention relates to a bearing seal system which prevents lubrication oil from leaking outside the beating section where the oil lubricates a beating to relatively rotatably support a rotating member against a fixed member.
b) Description of the Related Art
In recent years, a variety of bearings using oil as a lubricant such as genetic "slipping bearings" and hydrodynamic pressure bearings have been proposed. As an example of these products using such bearings, a motor for a hard disk drive system (HDD) of the fixed-shaft type is illustrated in FIG. 20. This motor has a rotatable hub 4 installed on a fixed shaft 2, which is fixed on a frame 1 via a radial bearing 3, so that a rotation lubrication oil is supplied to the space between fixed shaft 2 and radial bearing 3. The oil is retained inside the bearing section of the radial bearing 3 by capillary action.
Various rotation systems, in which a shaft rotates with lubrication oil such as a motor rotation shaft, always require oil leak prevention measures. Particularly, oil leakage is a serious problem for the bearings in HDD motors or laser beam printer (LBP) motors in which cleanliness is critical. The conventional bearing system is one in which oil is adhered only in the space of the bearing section by capillary action or a special sealing mechanism is used to prevent oil from leaking. However, these conventional technologies, for example, hydrodynamic pressure bearings, are unable to obtain a functional lubrication, such as a hydrodynamic pressure, when little lubrication oil is supplied and oil leaks when too much oil is supplied without appropriate oil leak prevention measures. Also in the conventional technology, the bearing seal system does not take into account external forces such as gravity, vibration, impact, centrifugal force, hydrodynamic pressure, atmospheric pressure, temperature and other pressures. This results in a system with poor dependability.